What kind of noise can I expect inside the car with the HFC DP and sport exhaust? I really want to wait for rear diffuser/quad outlet but I'm impatient so who knows.

At wide open throttle its going to have more noise of course and any drone is pretty close to stock levels at lower RPM at higher engine load or cruising speeds. We daily drove this car for a few months to test it in all conditions including hwy driving.

Challenge F30 335 Dyno Results for our HFC Downpipe combined with our Sports Catback Exhaust. We finally had a chance to get our F30 335 on the dyno again Friday and saw some great results even with the stock ECU. The car put down peak TQ gains of 30 ft lbs. with a solid 20-25 ft lbs. gain across majority of the powerband. Horsepower gains were 20-23hp peak and between 12-20 hp gains across most of the powerband. This means great usable power and gains at every RPM.